Ultra Low Power LCD Indicator - This circuit serves as an ultra-low power replacement for multiple LED on-off indicators. It also has the advantage of being easy to read in full daylight. With the parts shown, it is possible to display four bits of information. __ Designed by G. Forrest Cook

Unidirectional RF wireless transmitting & receiving - Digital in, digital out, with no wires!!! Yes, it can be that easy but there are some things you will find out about going wireless that you may not have counted with wired connection. This App Note will guide you through a simple RS232 link and illustrate how easy these devices are to use as long as you know how to handle a couple wireless phenomenon and plan your project to take these into account. __ Contact: info @ wzmicro.com

Uninterruptable Power Supply - This circuit is a simple form of the commercial UPS, the circuit provides a constant regulated 5 Volt output and an unregulated 12 Volt supply. In the event of electrical supply line failure the battery takes over, with __ Designed by Andy Collinson

Unipolar Stepper Motor Control - This circuit controls a small, four-phase, five-wire, unipolar stepper motor, commonly designated the "KP4M4-001. " This type of motor was used in many 5 1/4" floppy disk drives in older computers. Now obsolete, such disk drives are often available on the surplus market for a small fraction of the motor's original cost. The stepper motors are easy to extract from the drives, and are ideal for many applications. This arrangement was used in the scale model of a RADAR set to control the position of a miniature parabolic antenna. (Note that some 5 1/4" floppy disk drives used a four-wire "bipolar" motor, which is not compatible with this circuit.) __ Designed by Arthur Harrison

Unipolar Stepper Motor Controller - This is a very good integrated circuit. There is no need for any external glue logic to drive the circuit, there is only 2 pins to drive the motor, one for controlling the direction and the other to trigger the stepping pulses. It provides a very compact design that drives 5 or 6 or 8 wire stepper motors. The 5 or 8 wire stepper motors are treated as a variation on the 6 wire motor. That is, the 5 has the two common wires from the coils center taps joined inside the motor (saves joining them outside the motor) , __ Designed by R Ward

USB charger - I built this USB charger for my sister to charge her iPod without having to plug it into a computer. Apple do make their own version but 1) it costs many ££ and 2) it's fun to build your own! The actual iPod in question is a first generation iPod shuffle but this charger will work with any of the iPod's (having USB plug) or indeed, other kinds of USB devices which are in need of charging. __ Designed by Hans Summers

Use a PWM fan controller in an EMI-susceptible - 02/16/06 EDN-Design Ideas - Control it with either an external negative-temperature-coefficient thermistor or a PIC microcontroller and its SMBus serial-data bus __ Circuit Design by Dimitri Danyuk, Niles Audio Corp

Use a switching-regulator controller to generate fast pulses - 04/13/06 EDN-Design Ideas - Switching-regulator-controller ICs can deliver gate-drive pulses with rise and fall times of less than 2 nsec, making them ideal candidates for laboratory pulse-generators __ Circuit Design by Mitchell Lee, Linear Technology Corp

Using Pass Transistors Beef Up Voltage Regulator current output - Last month we learned how to make any fixed voltage regulator adjustable. However, many fixed regulators such as the 7805 limit their output current to 1.5 amps. While this may be adequate for many QRP transceivers, amateurs would often like to run a low power mobile 2 meter transceiver on their home-brew power supply. All that needs to be done is to add a couple of inexpensive pass transistors as in Figure 1.

Variable Threshold Solar Engine - The VTSE uses the popular 1381 chip and that is its main advantage. The potentiometer (or two fixed resistors) connects one leg between the output and input of the 1381 and the other leg to the supply voltage. These resistors acts like a voltage divider when the SE is off and the 1381 output is low. In that case, the voltage that appears at the 1381 input is determined by the ratio of the pot or the two resistors and is usually set for 2 times rated 1381 voltage. __ Designed by Wilf Rigter

Versatile Miniature High-Rate ESC with BEC & Brake - This electronic speed control (ESC) for brushed motors combines the features of two of my earlier designs. One was a high-rate 30A ESC with a brake, and the other a high-rate 12A ESC with a BEC (receiver battery eliminator circuit) . __ Designed by Stefan Vorketter

Very Basic 12 volt Inverter - This circuit will provide a fairly stable "Square Wave" Output Voltage. Frequency of operation is Mainly determined by the 220 uF Feedback Caps. Currently about 60 Hz. Various "off the shelf" transformers can be used. __ Designed by G.L. Chemelec

Voltage Comparator Switch - This circuit will provide an indication whenever the input voltage differs from two defined limits, V1 and V2. The supply voltage, Vcc must be higher than the highest input voltage by at least 2 volts. One application here is to monitor a 12V car battery __ Designed by Andy Collison

Voltage controllable LFO - This voltage-controlled LFO is based on the PIC 16F684, which is a pretty basic chip. Nonetheless, this LFO has more features than your average LFO. For a start, it can produce 7 basic waveforms, and also includes a noise source. It can also morph its waveforms under CV control, well beyond basic PWM

Voltage Controlled Solar Engine - Voltage-Controlled Solar Engine: These designs are based on the Motorola MC34164-* micro power undervoltage sensing ICs. They're pretty efficient, work at higher voltages than most solar engines, and can provide voltages for other logic circuits (say, a microprocessor) . This page hosts the original Chloroplast by Craig Maynard, as well as some Chloroplast variants by Wilf Rigter. __ Designed by Craig Maynard

Voltage doubler using a 555 timer - This circuit rougly doubles the voltage of the input, however the current output is low. doubled output is at 'V source. ' __ Designed by Andy Wilson

Voltage Inverter using 555 Timer - Simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input, extremely useful for powering OpAmp and other circuits that require a dual voltage from a single battery. __ Designed by Aaron Cake

Voltage Inverter using LM380 Audio Amplifier IC - This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input. It is therefore extremely useful for powering opamp and other circuits that require a dual voltage from a single battery. The circuit will operate at an input voltage from around 5V to 20V and produce a output from +-2.5V to +-10V. __ Designed by Aaron Cake

Voltage-doubling Solar Engine - The Vx2SE is a simple discrete voltage-doubling SE for driving an LED. If the load is a red or green LED, J1 is used together with just one red or green LED for threshold detection (no 1381) . For driving a blue LED use two green or red LEDs in series and may require a higher voltage (3V) solar cell. With 100uf capacitors the flash frequency is 2-3Hz and the R2 and R3 resistors may be omitted. With very large capacitors (0.01F and up) the frequency is much lower and the resistors can be optimized to stretch the LED "on" time. The Vx2 solar engines will self trigger but are also sensitive to a drop in light and will trigger from a shadow etc. __ Designed by Wilf Rigter

Vx2SE - Type 1 (Voltage Controlled) Solar Engine - The VTSE uses the popular 1381 chip and that is its main advantage. The potentiometer (or two fixed resistors) connects one leg between the output and input of the 1381 and the other leg to the supply voltage. These resistors acts like a voltage divider when the SE is off and the 1381 output is low. In that case, the voltage that appears at the 1381 input is determined by the ratio of the pot or the two resistors and is usually set for 2 times rated 1381 voltage. __ Designed by Wilf Rigter